2025/2026 Hybrid Powerunit speculation

[saviour stivala]

IN MY HUMBLE OPINION the regulations will not allow the engine to be run as a generator in stationary mode. Running the engine as a generator is a form of energy recovery, but it can only happen while the car is in motion, not when the car is stationary.

Is this statement in reference to my post? I don't think anyone is really concerned with that ...The only time a F1 car is stationary is at the start of the race and in the pit box. Going in and out of the pits it will be charging the battery, if it isn't full. Well, unless there is some rule I haven't heard of that prevents it. It will charge the battery under Saftey car and VSC conditions. etc etc etc .

Yes, when the car is not stationary, and provided it is moving above 50km/h (2026), the MGU-K can either charge the ES by harvesting energy, by use of brake pedal, or deploy energy to crankshaft, by use of accelerator pedal.

[wuzak]

Fortunately the ICE can make near full power with nowhere-near full boost - the extra boost is needed to maximise TE and eke out the last handful of ponies.

This goes against my understanding of forced induction.

A state-of-the-art 1.6 litre 6 cylinder racing engine with peak power at 10,500 rpm will have at least 200 KW. With 1 bar boost (2 Bar MAP) it will have 400+ KW. At this boost our F1 engine has reached its fuel flow limit so probably only makes 350 - 370 kW. The rules permit 4.8 Bar MAP but the extra boost is only used for leaning to increase TE. This TE increase gives our F1 engine the 400 - 440 KW we are expecting - not a lot more than it does at 2 Bar MAP.

I get an afr of ~8:1 at 10,500rpm with no boost, 100% volumetric efficiency.

What sort of afr would be required for stoichiometric? 12:1, 13:1?

So it wouldn't take much boost for them to be able to use the full fuel flow.

[Tommy Cookers]

This goes against my understanding of forced induction.

A state-of-the-art 1.6 litre 6 cylinder racing engine with peak power at 10,500 rpm will have at least 200 KW. With 1 bar boost (2 Bar MAP) it will have 400+ KW. At this boost our F1 engine has reached its fuel flow limit so probably only makes 350 - 370 kW. The rules permit 4.8 Bar MAP but the extra boost is only used for leaning to increase TE. This TE increase gives our F1 engine the 400 - 440 KW we are expecting - not a lot more than it does at 2 Bar MAP.

I get an afr of ~8:1 at 10,500rpm with no boost, 100% volumetric efficiency.
What sort of afr would be required for stoichiometric? 12:1, 13:1?
So it wouldn't take much boost for them to be able to use the full fuel flow.

is the Miller cycle disadvantageous in this aspect ? ('response' with low or no boost)

[Dr. Acula]

This goes against my understanding of forced induction.

A state-of-the-art 1.6 litre 6 cylinder racing engine with peak power at 10,500 rpm will have at least 200 KW. With 1 bar boost (2 Bar MAP) it will have 400+ KW. At this boost our F1 engine has reached its fuel flow limit so probably only makes 350 - 370 kW. The rules permit 4.8 Bar MAP but the extra boost is only used for leaning to increase TE. This TE increase gives our F1 engine the 400 - 440 KW we are expecting - not a lot more than it does at 2 Bar MAP.

I get an afr of ~8:1 at 10,500rpm with no boost, 100% volumetric efficiency.

What sort of afr would be required for stoichiometric? 12:1, 13:1?

So it wouldn't take much boost for them to be able to use the full fuel flow.

Stoichiometric with "normal" petrol would be 14.7:1. Possible that it's slightly different with the fuel that is used in F1.

[wuzak]

A state-of-the-art 1.6 litre 6 cylinder racing engine with peak power at 10,500 rpm will have at least 200 KW. With 1 bar boost (2 Bar MAP) it will have 400+ KW. At this boost our F1 engine has reached its fuel flow limit so probably only makes 350 - 370 kW. The rules permit 4.8 Bar MAP but the extra boost is only used for leaning to increase TE. This TE increase gives our F1 engine the 400 - 440 KW we are expecting - not a lot more than it does at 2 Bar MAP.

I get an afr of ~8:1 at 10,500rpm with no boost, 100% volumetric efficiency.

What sort of afr would be required for stoichiometric? 12:1, 13:1?

So it wouldn't take much boost for them to be able to use the full fuel flow.

Stoichiometric with "normal" petrol would be 14.7:1. Possible that it's slightly different with the fuel that is used in F1.

It's a synthetic/bio fuel that has lower energy density, so I would expect a different stoichiometric ratio.

[gruntguru]

This goes against my understanding of forced induction.

A state-of-the-art 1.6 litre 6 cylinder racing engine with peak power at 10,500 rpm will have at least 200 KW. With 1 bar boost (2 Bar MAP) it will have 400+ KW. At this boost our F1 engine has reached its fuel flow limit so probably only makes 350 - 370 kW. The rules permit 4.8 Bar MAP but the extra boost is only used for leaning to increase TE. This TE increase gives our F1 engine the 400 - 440 KW we are expecting - not a lot more than it does at 2 Bar MAP.

I get an afr of ~8:1 at 10,500rpm with no boost, 100% volumetric efficiency.
What sort of afr would be required for stoichiometric? 12:1, 13:1?
So it wouldn't take much boost for them to be able to use the full fuel flow.

Yes. Of course a state-of-the-art NA racing engine will have a VE of around 120% so your 8:1 becomes 9.6:1. Best power NA (varying fuel quantity) is at say 10.8:1 (assuming fuel has a stoich of 12) so they would be able to use about 90% of the max fuel allocation under these conditions. Somewhere around 0.1 Bar of boost (1.1 Bar MAP) they would need the full fuel allocation.

[mzso]

Fuel energy density must be between 38.0 MJ/kg and 41.0 MJ/kg. That's about 8% difference, so teh weight difference will be significant.

Only if you believe anyone is going to use fuel of much inferior energy density. I don't.

[wuzak]

Fuel energy density must be between 38.0 MJ/kg and 41.0 MJ/kg. That's about 8% difference, so teh weight difference will be significant.

Only if you believe anyone is going to use fuel of much inferior energy density. I don't.

They won't if there are efficiency gains using a formula with lower energy density.

They will probably aim for the highest energy density possible, but that's not to say that all fuel suppliers will achieve it.